private static decimal Execute(List <Token> inst, EvalContext param)
{
var stack = new Stack <object>();
object obj;
decimal d1, d2;
foreach (var token in inst)
{
switch (token.Type)
{
case TokenType.Number: stack.Push(Convert.ToDecimal(token.Value)); break;
case TokenType.ID:
if (param.TryGetValue(token.Value, out obj))
{
stack.Push(obj);
}
else
{
throw new Exception("ID '" + token.Value + "' not found.");
}
break;
case TokenType.Operator:
if (token.Tag == Tag.Unary)
{
d1 = Convert.ToDecimal(stack.Pop());
switch (token.Value)
{
case "+": stack.Push(d1); break;
case "-": stack.Push(-d1); break;
}
}
else
{
d2 = Convert.ToDecimal(stack.Pop());
d1 = Convert.ToDecimal(stack.Pop());
switch (token.Value)
{
case "+": stack.Push(d1 + d2); break;
case "-": stack.Push(d1 - d2); break;
case "*": stack.Push(d1 * d2); break;
case "/": stack.Push(d1 / d2); break;
}
}
break;
case TokenType.Dot:
throw new NotSupportedException();
case TokenType.CallStart: stack.Push(TokenType.CallStart); break;
case TokenType.CallEnd:
var p = new Stack <object>();
while (!TokenType.CallStart.Equals(obj = stack.Pop()))
{
p.Push(obj);
}
obj = (stack.Pop() as Delegate).DynamicInvoke(p.ToArray());
stack.Push(obj);
break;
}
}
return(stack.Count <= 0 ? 0 : Convert.ToDecimal(stack.Pop()));
}